Production of turbine or compressor blades



5 Sheets-Sheet 1 Inventor a v HORNE y Attorney Feb. 28, 1961 H. w. G. HlGNETT ET AL PRODUCTION OF TURBINE OR COMPRESSOR BLADES Filed Jan. 27, 1958 HAROLD WILLIAM GEoRGE r-MGNETT Pmup GORGE TuRuE-paAfl E (Lou g 1961 H. w. G. HlGNETT ET AL 2,972,806

PRODUCTION OF TURBINE OR COMPRESSOR BLADES 3 Sheets-Sheet 2 Filed Jan. 27, 1958 Inventor Huzow WILL/AH 6E0Q6E mcmzrr PHIL1P GEOQGE T RNER 04 HP BEL 1. 5 HOFVE v Attorney Feb. 28, 1961 H. W. G. HIGNETT ET AL PRODUCTION OF TURBINE OR COMPRESSOR BLADES 5 Sheets-Sheet 5 Filed Jan. 27, 1958 Un e S e ate T PRODUCTION OF TURBINE OR COMPRESSOR BLADES Harold W. G. Hignett, Harborne, Birmingham, and Philip George Turner, Inkberrow, England, and Campbell C. Horne, Glasgow, Scotland, assignors to The International Nickel Company, Inc., New York, N.Y., a corporation of Delaware Filed Jan. 27, 1958, Ser. No. 711,375 Claims priority, application Great Britain Jan. 30, 1957 7 Claims. (Cl. 29-156.8)

The present invention relates to the production of turbine blades and, more particularly, to the production of fluid-cooled turbine blades having cooling passages running therethrough.

It is an object of the present invention to provide a process for the production of fluid-cooled turbine blades having tapered cooling passages running therethrough.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing in which:

Figure 1 is a perspective view of one billet as used in accordance with the present invention;

Fig. 2 is an end view of this billet;

Fig. 3 shows the billet of Figure 1 after hot working;

Fig. 4 is a partial view of the hot worked billet of Fig. 3 after extrusion.

Fig. 5 shows the extruded billet of Fig. 4 after machining;

Fig. 6 shows the extruded billet of Fig. 4 after rolling;

Fig. 7 shows the air foil section of the final blade proper;

Fig. 8 shows another billet as used in accordance with the invention which is a variation of the billet of Figure 1;

Fig. 9 shows this second billet of Fig. 8 after hot working to uniform section in accordance with the invention;

Fig. 10 is a partial view of the worked billet of Fig. 9 after extrusion;

Figs. 11 and 12 show sections of the extruded second billet of Fig. 10 after machining and rolling, respectively;

Fig. 13 depicts a third billet which may be used in accordance with the present invention;

Fig. 14 shows the billet of Fig. 13 after hot working;

Fig. 15 shows a section on the line XV-XV.

Fig. 16 shows part of the blade blankextruded from this hot-worked billet; and

Figs. 17, 18, 19 and 20 are views of still another billet and correspond to Figs. 13 through 16 respectively.

Generally speaking, the present invention contemplates an improvement in a process for the production of a turbine (or compressor) blade with cooling passages extending longitudinally through it which comprises making or providing filled holes in a billet (or the like) of heat resistant metal, said holes being filled with a material having properties of flow similar to those of the billet, deforming the billet to alter the shape of the filled holes and thereafter removing the filler to leave the holes as the cooling passages. In a process of this kind, according to the invention, the billet initially tapers lengthwise over at least part of its length and the longitudinal filled holes in it extend through the tapering part and are of uniform cross section throughout their length, the tapering part of the billet is rendered substantially uniform in cross section by hot working, the holes thereupon becoming tapered, and this part of the billet is next extruded through a die of approximately airfoil section.

Patented Feb. 28, 1961 ice This part thus acquires the rough section required in the blade proper, i.e., becomes a blade blank, and there are tapering filled passages in it. Preferably, the extrusion is stopped while some of the billet is in the die, the unextruded part forming a blank for the root.

The holes may extend completely through the billet and, therefore, through the root and blade proper formed from the billet; and or they may be blind, i.e., extend only through part of the billet. If they are blind, the billet is preferably extruded with the holes leading, so that the blind part forms the root and holes may subsequently be made in the root to meet those in the blade proper; or the billet may be extruded with the blind part leading and this part may be upset to form a shroud through which holes are made to join those in the blade proper. If the whole billet is extruded, one end should be blind and later be upset to form the root.

In every case, the filed passages in the extruded bladeproper taper. This extruded part may be rolled so that it tapers in cross-sectional area from the root to the tip, the taper in the holes being thereby reduced or eliminated. Alternatively, this extruded part may be machined so that it tapers in crosssectional area from the root to the tip, the taper in the holes remaining unchanged. Thereafter, various well known machining, profiling, polishing, etc., operations may be performed on the blade blank to produce the final blade. The filler material is removed at any convenient stage following the working operations to provide cooling passages.

In carrying the invention into practice, the initial billet may be of various tapered shapes. Some of these are shown in the accompanying diagrammatic drawings. It should be appreciated, however, that one may roll a tapered oval section to the round or a frusto-cone to oval section provided there is some asymmetry in the transformation. Itis not practicable to roll a circular section to circular section.

Referring now to the drawing, the billet may be a truncated pyramid or rectangular section as shown at 1 in Figure l and blind holes 2 may be drilled in it parallel to one another and to the axis. There may, for instance, as shown in Fig. 2, be ten holes 2, of which only two are shown in Figure l and these holes are filled. The billet is then rolled to parallelepiped form as shown in Fig. 3 so that the holes taper towards their blind ends. The billet is now partially extruded to form a blade blank 3 of roughly airfoil section and a root blank 4. The

external shape so that the holes once more become substantially uniform in cross section throughout their length, as shown in Fig. 6. In either case, the cross section of the blade proper is illustrated by Fig. 7. The relative size of this section to that of the billet before extrusion is shown by the dotted lines in Fig. 2.

, The root blank 4 is converted to the desired shape, e.g.,- fir-tree, by machining with. or without preliminary forging and holes are then drilled in it to meet the holes in the blade proper.

The billet 1 shown in Fig. 8 is of the same shape as that in Fig. l, but the holes 2 in it are parallel to two of its opposed tapered sides. The result is that after conversion of the billet to the parallelepiped form shown in Fig. 9 and partial extrusion to the shape shown in Fig. 10, the billet has holes separated from one another by tapering metal 6. Figs. 11 and 12 are the equivalents of Figs. 5 and 6, respectively, Fig. 11 depicting the results of machining and Fig. 12 illustrating the results of rolling.

The billet may taper on only two opposite sides, i.e.,

. be a frustum of a wedge as shown in Fig. 13; The hot working then causes the holes 2 to change in cross-seetional shape as well as size as shown in Figs. 14 and 15 and after the extrusion they vary similarly, as shown in Fig. 16.

The holes 2 may be drilled from the large, rather than the small end of a billet, as shown in Fig. 17, with the result that after forging and partial extrusion of the billet, the holes vary in cross section size and shape in the ways diagrammatically illustrated by Figs. 18, 19 and 20, respectively.

For the purpose of giving those skilled in the art a better understanding of the invention (and/or a better appreciation of the advantages of the invention), the following illustrative examples are given:

Example I A tapered billet in the form of a frustu m of a wedge, base 2" x 1.65", top 2" x 1", height 2%" is drilled with one hole /2" diameter right through. The billet is made from an alloy of nickel chromium having the composition: carbon 0.1 max, titanium 1.8-3.0, chromium 18-21, aluminum 0.8-2.0, silicon 1.5 max, manganese 1.0 max., iron 5.0 max, cobalt 15-21, nickel balance. The hole is then filled with a filler of iron manganese titanium alloy, composition iron 80%, manganese 10%, titanium 2%. The tapered billet is then rolled at 1100 C.1l60 C. to parallelepiped form of rectangular section 2" x 1 length 3". The circular filled rod at the highly worked end becomes pseudo-elliptical with axes of 0.5" x 0.3". The billet is now partially extruded at 70 tons/ square inch with graphite lubricant at 1140 C.1160 C. to give a blade length of 6", having a blade section of chord 2" maximum thickness normal to the chord of /2". The unextruded root form is parallelepiped of 2" x 1" length l". The filler in the root is /2" diameter while the filler in the blade portion changes from a section near the root of pseudo-elliptical form having axes of /2" X A" to a section near the tip of pseudo-elliptical form ha'ving axes of 0.5" x 0.150". The filler in the blade being in effect of pseudo-conical form. The blade is then leached to remove the filler and machined to finished size with the requisite root fitting. It is to be appreciated that the example treats one hole for convenience only. In practice a plurality of holes would be drilled to give a blade of high Z factor for optimum cooling.

Example II A billet is prepared of parallelepiped form at the base, changing to a frustum of a wedge. Total height 2.175" base section 2" x 1.5" height 0.675. The truncated wedge portion is of base section 2" x 1.5" top section 2" x 1" height 1.5".

The billet is made in nickel-chromium alloy of the composition given in Example I. Two holes are drilled in the parallelepiped base of 0.175" diameter pitched apart 1.125" such that each hole is on the 1.5" centre line and 0.1875" from the edge. In the wedge portion the holes run parallel with the tapered wall and at the top are pitched apart on the 1" centre line a distance of 0.5. The holes are filled with filler rod of iron, manganese titanium having the composition iron 88%, manganese 10%, titanium 2%.

The billet is now rolled at 1100-1160 C. to the parallelepiped form having a section of 1" x 2" length 2.52". The holes in the wedge portion are thereby changed from circular section to pseudo-elliptical section and taper along their length on tapering centre lines. The billet is then partially extruded at 1140-1l60 C. with graphite lubricant to give a blade length of 3%" blade chord of 2 thickness 0.5" the root block is of 1" x 2 section length 1". The filler in the blade tapers and the centre lines of the filler are tapered within a parallel walled blade.

The blade is now rolled to taper over a length of with a thickness at the tip of A. The filler now lies on tapering centre lines parallel to the tapering wall of the blade. The filler per se being of substantially uniform section over its length. The blade is then leached and finish machined.

It is to be appreciated that in the examples reference to two holes is by way of ease of explanation only and in practice a plurality of holes would be drilled to give a blade of high Z factor suitable for use in high tem perature gas turbines where optimum cooling is desired.

With respect to the manufacture of turbine blades by means of the novel process, it should be understood that the term heat-resistant metal is used to include austenitic nickel-chromium alloys, including nickel-chro mium-iron and nickel-chromium-cobalt, and cobalt-chromium alloys, including cobalt-chromium-iron alloys, which contain a total of at least about 25% nickel plus chromium, cobalt plus chromium or nickel plus chromium plus cobalt (ie a total of at least about 25 of chromium plus nickel and/or cobalt) in addition to small amounts of aluminum, titanium, molybdenum, tungsten, vanadium, niobium, tantalum, silicon, manganese, Zirconium and boron which may optionally be present, either singly or in combination, in the alloys. These alloys are adapted to be subjected in use to temperatures up to about 700 C. or above and, accordingly, must be hot worked at temperatures around 1200 C. Fillers adapted to cooperate with such heat-resistant metal may be fern'tic alloys of iron, manganese and titanium containing from about 5% to about 20% manganese, about 1% to about 10% titanium with the balance essentially iron. Other fillers may be mixtures of ceramic material such as magnesia "and metal such as iron, with the metal being the continuous phase and the ceramic material constituting between about 5% and 25 of the composition by weight.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

We claim:

1. A process for the production of a turbine blade blank which comprises providing a tapered metal billet having a larger cross-sectional area at one end than the other end and having holes of substantially uniform cross-sectional area which are filled With a filler having deformation characteristics similar to the deformation characteristics of the metal of said billet and which extend from one of said ends toward the other, hot working said tapered metal billet in a direction parallel to the direction of said filled holes-to provide a worked billet having a substantially uniform cross section and thereby tapering said filled holes so that said filled holes have a larger cross-sectional area at one end than the other end, deforming the billet of uniform cross-sectional area so produced to provide a turbine blade blank and thereafter removing the filler from the filled holes in said blank to provide tapered cooling passages therein.

2. A process as set forth and defined in claim 1, wherein the filled holes in the tapered metal billet are inclined parallel to the sides of the tapered metal billet.

3. A process as set forth and defined in claim 1, wherein the tapered billet is hot worked by rolling and the billet of uniform cross-sectional area so produced is extruded to form the turbine blade blank.

4. A process for the production of a turbine blade blank which comprises providing a tapered rectangular metal billet having a larger cross-sectional area at one end than the other end and having substantially longitudinal holes of substantially uniform cross-sectional area which are filled with a filler having deformation characteristics similar to the deformation characteristics of the metal of said billet and which extend from one of said ends toward the other, hot rolling said tapered metal billet in a direction parallel to the direction of said filled holes to provide a rolled billet having a substantially uniform cross section and thereby tapering said filled holes so that said filled holes have a larger cross-sectional area at one end than the other end, extruding the billet of uniform cross-sectional area so produced to provide a turbine blade blank and thereafter removing the filler from the filled holes in said blank to provide tapered cooling passages therein.

5-. A process as set forth and defined in claim 4, wherein the tapered billet is a frustum of a rectangular pyramid.

6. A process as set forth and defined in claim 4, wherein the tapered billet is a frustum of a wedge.

7. A process for the production of a turbine blade blank which comprises providing a tapered rounded metal billet having a larger cross-sectional area at one end than the other end and having substantially longitudinal holes of substantially uniform cross-sectional area which are filled with a filler having deformation characten'stics similar to the deformation characteristics of the metal of said billet and which extend from one of said ends toward the other, hot rolling said tapered metal billet in a direction parallel to the direction of said filled holes to provide a rolled billet having a substantially uniform cross section and thereby tapering said filled holes so that said filled holes have a larger cross-sectional area at one end than the other end, extruding the billet of uniform cross-sectional. area so produced to provide a turbine blade blank and thereafter removing the-filler from the filled holes in said blank to provide tapered cooling passages therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,019,191 Russell Mar. 5, 1912 2,628,417 Peyches Feb. 17, 1953 FOREIGN PATENTS 739,499 Great Britain Nov. 2, ;1955 755,610 Great Britain Aug. 22, 1956 

